A common method used by criminals to trick victims is the fake invoice.
You may receive an email from a typically unknown sender, informing you that an invoice is overdue and has not been paid. Usually such emails will include the invoice in question as an attachment.
Most people would be concerned to receive such an email, and many will open the attachment to see what’s outstanding. Unfortunately, these attachments will often contain malware which will be installed on your device simply by opening the file.
Some such scams will use the opportunity to harvest your bank or credit card details directly from you as a form of payment, whilst others will use malware to encrypt your files and demand payment in order to restore your access.
Be wary of any unexpected invoices by email. Always take a cautious approach, and consider that such emails may be an attempt to trick you.